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Kwon HI, Do DT, Van Vo H, Lee SC, Kim MH, Nguyen DTT, Tran TM, Le QTV, Ngo TTN, Nguyen NM, Lee JY, Nguyen TT. Development of optimized protocol for culturing African swine fever virus field isolates in MA104 cells. Can J Vet Res 2022; 86:261-268. [PMID: 36211218 PMCID: PMC9536354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 03/23/2022] [Indexed: 04/03/2023]
Abstract
The goal of this study was to identify a candidate commercial cell line for the replication of African swine fever virus (ASFV) by comparing several available cell lines with various medium factors. In the sensitivity test of cells, MA104 and MARC-145 had strong potential for ASFV replication. Next, MA104 cells were used to compare the adaptation of ASFV obtained from tissue homogenates and blood samples in various infectious media. At the 10th passage, the ASFV obtained from the blood sample had a significantly higher viral load than that obtained from the tissue sample (P = 0.000), exhibiting a mean cycle threshold (Ct) value = 20.39 ± 1.99 compared with 25.36 ± 2.11. For blood samples, ASFV grew on infectious medium B more robustly than on infectious medium A (P = 0.006), corresponding to a Ct value = 19.58 ± 2.10 versus 21.20 ± 1.47. African swine fever virus originating from blood specimens continued to multiply gradually and peaked in the 15th passage, exhibiting a Ct value = 14.36 ± 0.22 in infectious medium B and a Ct value = 15.42 ± 0.14 in infectious medium A. When ASFV was cultured from tissue homogenates, however, there was no difference (P = 0.062) in ASFV growth between infectious media A and B. A model was developed to enhance ASFV replication through adaptation to MA104 cells. The lack of mutation at the genetic segments encoding p72, p54, p30, and the central hypervariable region (CVR) in serial culture passages is important in increasing the probability of maintaining immunogenicity when developing a vaccine candidate.
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Affiliation(s)
- Hyeok-Il Kwon
- ChoongAng Vaccine Laboratories, Daejeon, 34055, Republic of Korea (Hyeok-il Kwon, Seung-Chul Lee, Min Ho Kim, Joo Young Lee); Department of Infectious Diseases and Veterinary Public Health, Faculty of Animal Science and Veterinary Medicine, Nong Lam University, Thu Duc District, Ho Chi Minh City, Vietnam (Duy Tien Do, Dung Thi Thuy Nguyen, Tram Thi Ngoc Ngo, Toan Tat Nguyen); Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Department of Animal Health, Vietnam (Hung Van Vo, Tan Minh Tran, Quang Tin Vinh Le); Research Center for Genetics and Reproductive Health (CGRH), School of Medicine, National University HCMC, Vietnam, (Nam Minh Nguyen)
| | - Duy Tien Do
- ChoongAng Vaccine Laboratories, Daejeon, 34055, Republic of Korea (Hyeok-il Kwon, Seung-Chul Lee, Min Ho Kim, Joo Young Lee); Department of Infectious Diseases and Veterinary Public Health, Faculty of Animal Science and Veterinary Medicine, Nong Lam University, Thu Duc District, Ho Chi Minh City, Vietnam (Duy Tien Do, Dung Thi Thuy Nguyen, Tram Thi Ngoc Ngo, Toan Tat Nguyen); Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Department of Animal Health, Vietnam (Hung Van Vo, Tan Minh Tran, Quang Tin Vinh Le); Research Center for Genetics and Reproductive Health (CGRH), School of Medicine, National University HCMC, Vietnam, (Nam Minh Nguyen)
| | - Hung Van Vo
- ChoongAng Vaccine Laboratories, Daejeon, 34055, Republic of Korea (Hyeok-il Kwon, Seung-Chul Lee, Min Ho Kim, Joo Young Lee); Department of Infectious Diseases and Veterinary Public Health, Faculty of Animal Science and Veterinary Medicine, Nong Lam University, Thu Duc District, Ho Chi Minh City, Vietnam (Duy Tien Do, Dung Thi Thuy Nguyen, Tram Thi Ngoc Ngo, Toan Tat Nguyen); Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Department of Animal Health, Vietnam (Hung Van Vo, Tan Minh Tran, Quang Tin Vinh Le); Research Center for Genetics and Reproductive Health (CGRH), School of Medicine, National University HCMC, Vietnam, (Nam Minh Nguyen)
| | - Seung-Chul Lee
- ChoongAng Vaccine Laboratories, Daejeon, 34055, Republic of Korea (Hyeok-il Kwon, Seung-Chul Lee, Min Ho Kim, Joo Young Lee); Department of Infectious Diseases and Veterinary Public Health, Faculty of Animal Science and Veterinary Medicine, Nong Lam University, Thu Duc District, Ho Chi Minh City, Vietnam (Duy Tien Do, Dung Thi Thuy Nguyen, Tram Thi Ngoc Ngo, Toan Tat Nguyen); Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Department of Animal Health, Vietnam (Hung Van Vo, Tan Minh Tran, Quang Tin Vinh Le); Research Center for Genetics and Reproductive Health (CGRH), School of Medicine, National University HCMC, Vietnam, (Nam Minh Nguyen)
| | - Min Ho Kim
- ChoongAng Vaccine Laboratories, Daejeon, 34055, Republic of Korea (Hyeok-il Kwon, Seung-Chul Lee, Min Ho Kim, Joo Young Lee); Department of Infectious Diseases and Veterinary Public Health, Faculty of Animal Science and Veterinary Medicine, Nong Lam University, Thu Duc District, Ho Chi Minh City, Vietnam (Duy Tien Do, Dung Thi Thuy Nguyen, Tram Thi Ngoc Ngo, Toan Tat Nguyen); Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Department of Animal Health, Vietnam (Hung Van Vo, Tan Minh Tran, Quang Tin Vinh Le); Research Center for Genetics and Reproductive Health (CGRH), School of Medicine, National University HCMC, Vietnam, (Nam Minh Nguyen)
| | - Dung Thi Thuy Nguyen
- ChoongAng Vaccine Laboratories, Daejeon, 34055, Republic of Korea (Hyeok-il Kwon, Seung-Chul Lee, Min Ho Kim, Joo Young Lee); Department of Infectious Diseases and Veterinary Public Health, Faculty of Animal Science and Veterinary Medicine, Nong Lam University, Thu Duc District, Ho Chi Minh City, Vietnam (Duy Tien Do, Dung Thi Thuy Nguyen, Tram Thi Ngoc Ngo, Toan Tat Nguyen); Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Department of Animal Health, Vietnam (Hung Van Vo, Tan Minh Tran, Quang Tin Vinh Le); Research Center for Genetics and Reproductive Health (CGRH), School of Medicine, National University HCMC, Vietnam, (Nam Minh Nguyen)
| | - Tan Minh Tran
- ChoongAng Vaccine Laboratories, Daejeon, 34055, Republic of Korea (Hyeok-il Kwon, Seung-Chul Lee, Min Ho Kim, Joo Young Lee); Department of Infectious Diseases and Veterinary Public Health, Faculty of Animal Science and Veterinary Medicine, Nong Lam University, Thu Duc District, Ho Chi Minh City, Vietnam (Duy Tien Do, Dung Thi Thuy Nguyen, Tram Thi Ngoc Ngo, Toan Tat Nguyen); Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Department of Animal Health, Vietnam (Hung Van Vo, Tan Minh Tran, Quang Tin Vinh Le); Research Center for Genetics and Reproductive Health (CGRH), School of Medicine, National University HCMC, Vietnam, (Nam Minh Nguyen)
| | - Quang Tin Vinh Le
- ChoongAng Vaccine Laboratories, Daejeon, 34055, Republic of Korea (Hyeok-il Kwon, Seung-Chul Lee, Min Ho Kim, Joo Young Lee); Department of Infectious Diseases and Veterinary Public Health, Faculty of Animal Science and Veterinary Medicine, Nong Lam University, Thu Duc District, Ho Chi Minh City, Vietnam (Duy Tien Do, Dung Thi Thuy Nguyen, Tram Thi Ngoc Ngo, Toan Tat Nguyen); Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Department of Animal Health, Vietnam (Hung Van Vo, Tan Minh Tran, Quang Tin Vinh Le); Research Center for Genetics and Reproductive Health (CGRH), School of Medicine, National University HCMC, Vietnam, (Nam Minh Nguyen)
| | - Tram Thi Ngoc Ngo
- ChoongAng Vaccine Laboratories, Daejeon, 34055, Republic of Korea (Hyeok-il Kwon, Seung-Chul Lee, Min Ho Kim, Joo Young Lee); Department of Infectious Diseases and Veterinary Public Health, Faculty of Animal Science and Veterinary Medicine, Nong Lam University, Thu Duc District, Ho Chi Minh City, Vietnam (Duy Tien Do, Dung Thi Thuy Nguyen, Tram Thi Ngoc Ngo, Toan Tat Nguyen); Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Department of Animal Health, Vietnam (Hung Van Vo, Tan Minh Tran, Quang Tin Vinh Le); Research Center for Genetics and Reproductive Health (CGRH), School of Medicine, National University HCMC, Vietnam, (Nam Minh Nguyen)
| | - Nam Minh Nguyen
- ChoongAng Vaccine Laboratories, Daejeon, 34055, Republic of Korea (Hyeok-il Kwon, Seung-Chul Lee, Min Ho Kim, Joo Young Lee); Department of Infectious Diseases and Veterinary Public Health, Faculty of Animal Science and Veterinary Medicine, Nong Lam University, Thu Duc District, Ho Chi Minh City, Vietnam (Duy Tien Do, Dung Thi Thuy Nguyen, Tram Thi Ngoc Ngo, Toan Tat Nguyen); Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Department of Animal Health, Vietnam (Hung Van Vo, Tan Minh Tran, Quang Tin Vinh Le); Research Center for Genetics and Reproductive Health (CGRH), School of Medicine, National University HCMC, Vietnam, (Nam Minh Nguyen)
| | - Joo Young Lee
- ChoongAng Vaccine Laboratories, Daejeon, 34055, Republic of Korea (Hyeok-il Kwon, Seung-Chul Lee, Min Ho Kim, Joo Young Lee); Department of Infectious Diseases and Veterinary Public Health, Faculty of Animal Science and Veterinary Medicine, Nong Lam University, Thu Duc District, Ho Chi Minh City, Vietnam (Duy Tien Do, Dung Thi Thuy Nguyen, Tram Thi Ngoc Ngo, Toan Tat Nguyen); Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Department of Animal Health, Vietnam (Hung Van Vo, Tan Minh Tran, Quang Tin Vinh Le); Research Center for Genetics and Reproductive Health (CGRH), School of Medicine, National University HCMC, Vietnam, (Nam Minh Nguyen)
| | - Toan Tat Nguyen
- ChoongAng Vaccine Laboratories, Daejeon, 34055, Republic of Korea (Hyeok-il Kwon, Seung-Chul Lee, Min Ho Kim, Joo Young Lee); Department of Infectious Diseases and Veterinary Public Health, Faculty of Animal Science and Veterinary Medicine, Nong Lam University, Thu Duc District, Ho Chi Minh City, Vietnam (Duy Tien Do, Dung Thi Thuy Nguyen, Tram Thi Ngoc Ngo, Toan Tat Nguyen); Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Department of Animal Health, Vietnam (Hung Van Vo, Tan Minh Tran, Quang Tin Vinh Le); Research Center for Genetics and Reproductive Health (CGRH), School of Medicine, National University HCMC, Vietnam, (Nam Minh Nguyen)
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Oh T, Do DT, Vo HV, Kwon HI, Lee SC, Kim MH, Nguyen DTT, Le QTV, Tran TM, Nguyen TT, Lee JY, Chae C. The Isolation and Replication of African Swine Fever Virus in Primary Renal-Derived Swine Macrophages. Front Vet Sci 2021; 8:645456. [PMID: 33816588 PMCID: PMC8017199 DOI: 10.3389/fvets.2021.645456] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 02/26/2021] [Indexed: 02/04/2023] Open
Abstract
African swine fever virus (ASFV) causes hemorrhagic disease in domestic pigs by replicating mainly in monocyte/macrophage lineages. Various primary cells including pulmonary alveolar macrophages have been used for the propagation of ASFV on this account. However, ethical constraints and consistency problems exist as it is necessary to harvest same phenotype of primary cells in order to continue a study. We suggested renal-derived swine macrophages as a novel primary cell candidate to address these issues. These primary cells proved to be permissive to both cell adapted ASFV and a wild-type ASFV. Compared to the commercial cell line MA-104, the renal-derived macrophages were more suitable to isolate the field virus. The consistent molecular characteristics of the renal-derived macrophages were demonstrated by immunocytochemistry with antibodies against macrophage cell surface markers including CD163, CD172a, and Iba-1. Viral protein p30 and p72 expression in ASFV infected macrophages was confirmed by immunocytochemistry by use of specific monoclonal antibodies. We observed increase of cell-free viral DNA and infectious virus titer in infected cell supernatant in successive days-post-infection. These results demonstrated that primary renal-derived swine macrophages are useful for ASFV isolation and propagation in terms of cell phenotypes, susceptibility to the virus, and virus production.
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Affiliation(s)
- Taehwan Oh
- Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, Seoul, South Korea
| | - Duy Tien Do
- Faculty of Animal Sciences and Veterinary Medicine, Nong Lam University, Ho Chi Minh City, Vietnam
| | - Hung Van Vo
- Department of Animal Health, Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Vietnam
| | - Hyeok-Il Kwon
- ChoongAng Vaccine Laboratories, Daejeon, South Korea
| | | | - Min Ho Kim
- ChoongAng Vaccine Laboratories, Daejeon, South Korea
| | - Dung Thi Thu Nguyen
- Faculty of Animal Sciences and Veterinary Medicine, Nong Lam University, Ho Chi Minh City, Vietnam
| | - Quang Tin Vinh Le
- Department of Animal Health, Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Vietnam
| | - Tan Minh Tran
- Department of Animal Health, Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Vietnam
| | - Toan Tat Nguyen
- Faculty of Animal Sciences and Veterinary Medicine, Nong Lam University, Ho Chi Minh City, Vietnam
| | - Joo Young Lee
- ChoongAng Vaccine Laboratories, Daejeon, South Korea
| | - Chanhee Chae
- Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, Seoul, South Korea
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Takemae N, Nguyen PT, Le VT, Nguyen TN, To TL, Nguyen TD, Pham VP, Vo HV, Le QVT, Do HT, Nguyen DT, Uchida Y, Saito T. Appearance of reassortant European avian-origin H1 influenza A viruses of swine in Vietnam. Transbound Emerg Dis 2018; 65:1110-1116. [PMID: 29512309 DOI: 10.1111/tbed.12849] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Indexed: 11/26/2022]
Abstract
Three subtypes-H1N1, H1N2 and H3N2-of influenza A viruses of swine (IAVs-S) are currently endemic in swine worldwide, but there is considerable genotypic diversity among each subtype and limited geographical distribution. Through IAVs-S monitoring in Vietnam, two H1N2 influenza A viruses were isolated from healthy pigs in Ba Ria-Vung Tau Province, Southern Vietnam, on 2 December 2016. BLAST and phylogenetic analyses revealed that their HA and NA genes were derived from those of European avian-like H1N2 IAVs-S that contained avian-origin H1 and human-like N2 genes, and were particularly closely related to those of IAVs-S circulating in the Netherlands, Germany or Denmark. In addition, the internal genes of these Vietnamese isolates were derived from human A(H1N1)pdm09 viruses, suggesting that the Vietnamese H1N2 IAVs-S are reassortants between European H1N2 IAVs-S and human A(H1N1)pdm09v. The appearance of European avian-like H1N2 IAVs-S in Vietnam marks their first transmission outside Europe. Our results and statistical analyses of the number of live pigs imported into Vietnam suggest that the European avian-like H1N2 IAVs-S may have been introduced into Vietnam with their hosts through international trade. These findings highlight the importance of quarantining imported pigs to impede the introduction of new IAVs-S.
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Affiliation(s)
- N Takemae
- Division of Transboundary Animal Disease, National Institute of Animal Health, NARO, Tsukuba, Japan
- Thailand-Japan Zoonotic Diseases Collaboration Center, Bangkok, Thailand
| | - P T Nguyen
- Regional Animal Health Office No. 6, Department of Animal Health, Ho Chi Minh City, Vietnam
| | - V T Le
- Regional Animal Health Office No. 6, Department of Animal Health, Ho Chi Minh City, Vietnam
| | - T N Nguyen
- Epidemiology Division, Department of Animal Health, Hanoi, Vietnam
| | - T L To
- National Centre for Veterinary Diagnostics, Department of Animal Health, Hanoi, Vietnam
| | - T D Nguyen
- National Centre for Veterinary Diagnostics, Department of Animal Health, Hanoi, Vietnam
| | - V P Pham
- Regional Animal Health Office No. 6, Department of Animal Health, Ho Chi Minh City, Vietnam
| | - H V Vo
- Regional Animal Health Office No. 6, Department of Animal Health, Ho Chi Minh City, Vietnam
| | - Q V T Le
- Regional Animal Health Office No. 6, Department of Animal Health, Ho Chi Minh City, Vietnam
| | - H T Do
- National Centre for Veterinary Diagnostics, Department of Animal Health, Hanoi, Vietnam
| | - D T Nguyen
- Epidemiology Division, Department of Animal Health, Hanoi, Vietnam
| | - Y Uchida
- Division of Transboundary Animal Disease, National Institute of Animal Health, NARO, Tsukuba, Japan
- Thailand-Japan Zoonotic Diseases Collaboration Center, Bangkok, Thailand
| | - T Saito
- Division of Transboundary Animal Disease, National Institute of Animal Health, NARO, Tsukuba, Japan
- Thailand-Japan Zoonotic Diseases Collaboration Center, Bangkok, Thailand
- United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan
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Takemae N, Shobugawa Y, Nguyen PT, Nguyen T, Nguyen TN, To TL, Thai PD, Nguyen TD, Nguyen DT, Nguyen DK, Do HT, Le TQA, Hua PT, Van Vo H, Nguyen DT, Nguyen DH, Uchida Y, Saito R, Saito T. Effect of herd size on subclinical infection of swine in Vietnam with influenza A viruses. BMC Vet Res 2016; 12:227. [PMID: 27724934 PMCID: PMC5057248 DOI: 10.1186/s12917-016-0844-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 02/18/2016] [Indexed: 01/14/2023] Open
Abstract
Background Influenza A viruses of swine (IAV-S) cause acute and subclinical respiratory disease. To increase our understanding of the etiology of the subclinical form and thus help prevent the persistence of IAV-S in pig populations, we conducted active virologic surveillance in Vietnam, the second-largest pig-producing country in Asia, from February 2010 to December 2013. Results From a total of 7034 nasal swabs collected from clinically healthy pigs at 250 farms and 10 slaughterhouses, we isolated 172 IAV-S from swine at the weaning and early-fattening stages. The isolation rate of IAV-S was significantly higher among pigs aged 3 weeks to 4.5 months than in older and younger animals. IAV-S were isolated from 16 large, corporate farms and 6 family-operated farms from among the 250 farms evaluated. Multivariate logistic regression analysis revealed that “having more than 1,000 pigs” was the most influential risk factor for IAV-S positivity. Farms affected by reassortant IAV-S had significantly larger pig populations than did those where A(H1N1)pdm09 viruses were isolated, thus suggesting that large, corporate farms serve as sites of reassortment events. Conclusions We demonstrate the asymptomatic circulation of IAV-S in the Vietnamese pig population. Raising a large number of pigs on a farm has the strongest impact on the incidence of subclinical IAV-S infection. Given that only some of the corporate farms surveyed were IAV-S positive, further active monitoring is necessary to identify additional risk factors important in subclinical infection of pigs with IAV-S in Vietnam. Electronic supplementary material The online version of this article (doi:10.1186/s12917-016-0844-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nobuhiro Takemae
- Influenza and Prion Diseases Research Center, National Institute of Animal Health, NARO, Ibaraki, Japan.,Thailand-Japan Zoonotic Diseases Collaboration Center, Bangkok, Thailand
| | - Yugo Shobugawa
- Division of International Health, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Phuong Thanh Nguyen
- Department of Animal Health, Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Vietnam
| | - Tung Nguyen
- Department of Animal Health, Epidemiology Division, Hanoi, Vietnam
| | - Tien Ngoc Nguyen
- Department of Animal Health, Epidemiology Division, Hanoi, Vietnam
| | - Thanh Long To
- Department of Animal Health, National Centre for Veterinary Diagnostics, Hanoi, Vietnam
| | - Phuong Duy Thai
- Department of Animal Health, Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Vietnam
| | - Tho Dang Nguyen
- Department of Animal Health, National Centre for Veterinary Diagnostics, Hanoi, Vietnam
| | - Duy Thanh Nguyen
- Department of Animal Health, Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Vietnam
| | - Dung Kim Nguyen
- Department of Animal Health, Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Vietnam
| | - Hoa Thi Do
- Department of Animal Health, National Centre for Veterinary Diagnostics, Hanoi, Vietnam
| | - Thi Quynh Anh Le
- Department of Animal Health, Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Vietnam
| | - Phan Truong Hua
- Department of Animal Health, Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Vietnam
| | - Hung Van Vo
- Department of Animal Health, Center for Veterinary Diagnostics, Regional Animal Health Office No. 6, Ho Chi Minh City, Vietnam
| | - Diep Thi Nguyen
- Department of Animal Health, Epidemiology Division, Hanoi, Vietnam
| | - Dang Hoang Nguyen
- Department of Animal Health, National Centre for Veterinary Diagnostics, Hanoi, Vietnam
| | - Yuko Uchida
- Influenza and Prion Diseases Research Center, National Institute of Animal Health, NARO, Ibaraki, Japan.,Thailand-Japan Zoonotic Diseases Collaboration Center, Bangkok, Thailand
| | - Reiko Saito
- Division of International Health, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Takehiko Saito
- Influenza and Prion Diseases Research Center, National Institute of Animal Health, NARO, Ibaraki, Japan. .,Thailand-Japan Zoonotic Diseases Collaboration Center, Bangkok, Thailand. .,United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan.
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